A wide variety of natural and synthetic filling materials for thermal insulation applications, such as in outerwear, e.g., ski jackets and snowmobile suits, sleeping bags, and bedding, e.g., comforters and bedspreads, are known.
Natural feather down has found wide acceptance for thermal insulation applications, primarily because of its outstanding weight efficiency and resilience. Properly fluffed and contained in an envelope to control migration within a garment, down is generally recognized as the insulation material of choice. However, down compacts and loses its insulating properties when it becomes wet and exhibits a rather unpleasant odor when exposed to moisture. Also a carefully controlled cleaning and drying process is required to restore the fluffiness and resultant thermal insulating properties to a garment in which the down has compacted.
There have been numerous attempts to prepare synthetic fiber-based substitutes for down which would have equivalent thermal insulating performance without the moisture sensitivity of natural down.
U.S. Pat. No. 3,892,909 (Miller) discloses fibrous bodies simulating natural bird down which include larger circular bodies, or figures of revolution, and smaller feather bodies, the feathery bodies tending to fill the voids formed by the larger circular bodies. The fibrous bodies are preferably formed from synthetic fiber tow.
U.S Pat. No. 4,588,635 (Donovan) describes synthetic down thermal insulating materials which are batts of plied card-laps of a blend of 80 to 95 weight percent of spun and drawn, crimped, staple, synthetic polymeric microfibers having a diameter of from 3 to 12 microns and 5 to 20 weight percent of synthetic polymeric staple macrofibers having a diameter of from more than 12, up to 50 microns. Donovan describes this fiber blend as comparing favorably to down or mixtures of down with feathers as an insulator in that it will provide an equally efficient thermal barrier, be of equivalent density, possess similar compression properties, have improved wetting and drying characteristics, and have superior loft retention while wet. These batts are formed by physical entanglement of the fibers achieved during carding. An expanded discussion of these same materials can be found in Dent, Robin W. et al., DEVELOPMENT OF SYNTHETIC DOWN ALTERNATIVES, Technical Report Natick/TR-86/021L--Final Report, Phase 1.
U.S. Pat. No. 4,392,903 (Endo et al.) discloses a thermal insulating bulky product which has a structural make-up of substantially continuous, single fine filaments of from about 0.01 to about 2 deniers which are stabilized in the product by a surface binder. Generally, the binder is a thermoplastic polymer such as polyvinyl alcohol or polyacrylic esters which is deposited on the filaments as a mist of minute particles of emulsion before accumulation of the filaments.
U.S. Pat. No. 4,118,531 (Hauser) discloses a thermal insulating material which is a web of blended microfibers with crimped bulking fibers which are randomly and thoroughly intermixed and intertangled with the microfibers. The crimped bulking fibers are generally introduced into a stream of blown microfibers prior to their collection. This web combines high thermal resistance per unit of thickness and moderate weight.
U.S. Pat. No. 4,418,103 (Tani et al.) discloses the preparation of a synthetic filling material composed of an assembly of crimped monofilament fibers having crimps located in mutually deviated phases, which fibers are bonded together at one end to achieve a high density portion, while the other ends of the fibers stay free. This fill material is described as having superior bulkiness and thermal insulation properties. This filling material is described as being suitable for filling a mattress, bed, pad, cushion pillow, stuffed doll, sofa, or the like, as well as being a down substitute suitable for filling jackets, sleeping bags, ski wear, and night gowns.
U.S. Pat. No. 4,259,400 (Bolliand) discloses a fibrous padding material simulating natural down, the material being in the form of a central filiform core which is relatively dense and rigid and to which are bonded fibers which are oriented substantially transversely relative to this core, the fibers being entangled with one another so as to form a homogeneous thin web and being located on either side of the core, substantially in the same plane.
U.S. Pat. No. 4,433,019 (Chumbley) discloses another approach to thermal insulating fabrics wherein staple fiber is needle-punched through a metallized polymeric film and through a nonwoven polyester sheet and the film and sheet are placed adjacent to each other such that the needle-punched fibers protrude from each face of the fabric to produce a soft, breathable fleece-like material.
U.S. Pat. No. 4,065,599 (Nishiumi et al.) discloses down-like synthetic filler material comprising spherical objects made up of filamentary material with a denser concentration of filaments near the surface of the spherical object than the filament concentration spaced apart from the surface.
U.S. Pat. No. 4,144,294 (Werthaiser et al.) discloses a substitute for natural down comprising sheets of garneted polyester which are separated into a plurality of small pieces, each of which pieces is generally formed into a rounded body. Each of the rounded bodies include a plurality of randomly oriented polyester fibers therein, and each of the rounded bodies provides a substantial resiliency to permanent deformation after the application of force to them.
U.S. Pat. No. 4,618,531 (Marcus) discloses polyester fiberfill having spiral-crimp that is randomly arranged and entangled in the form of fiberballs with a minimum of hairs extending from their surface, and having a refluffable characteristic similar to that of down.
U.S. Pat. No. 3,905,057 (Willis et al.) discloses a fiber-filled pillow wherein the fibrous pillow batt has substantially all its fiber oriented parallel to one another and perpendicular to a plane bisecting a vertical cross-section of the pillow. A pillow casing is used to enclose these batts and to keep them in a useful configuration. These fiber-filled pillows are described as having a high degree of resiliency and fluffability, but are not contemplated as thermal insulation materials.